1. Field of the Invention
This invention relates to temporary indicators affixed to light transmitting substrates.
2. Description of the Prior Art
Light transmitting substrates in the form of transparencies, x-ray film, positive photograhic film and the like are useful in conveying information. In use, these substrates are viewed with a source of light placed behind them. Very often, to call attention to a portion of the substrate, a person would touch the surface of the substrate with a finger, a pointing device, pencil or marker. This practice can, and often does, result in permanent scratches and nicks on the substrate surfaces The use of grease pencils and china markers often results in marks which are most difficult to remove. By the same token, the marks made by felt tipped pens and ball point pens are seldom removed without permanent damage to the substrate surface. Any of the foregoing damage is most objectionable when the substrate is an x-ray, positive film or the like that cannot be replaced. The marks are also objectionable to the further use of the x-ray and its diagnostic value simply because they obscure, if not completely masks out, the data on the substrate. Additionlly, marks can be misleading when the substrate is referred to a second party for independent consideration. Thus, a means for pointing out portions of interest on the substrate and yet both lessen damage and increase useability of substrate data is needed. The pointing means must be useable at all degrees of elevation from the horizontal since overhead viewers are designed for use with a flat, horizontal transparency and x-rays are typically viewed with a view box having a generally vertical viewing surface.